1. Background Field
The present disclosure generally relates to radio frequency (RF) communications. More particularly, the present disclosure relates to multiplexing a first (e.g., global positioning system (GPS)) signal and a second (e.g., cellular paging signal) on a single receiver RF chain. In addition, the present invention relates to multiplexing a signal (e.g., global positioning system (GPS) signal) between two different receiver RF chains.
2. Relevant Background
In radio frequency (RF) communication applications, an RF receiver or a receiver portion of an RF transceiver is an electronic circuit that receives an input from an antenna, and uses electronic filters to separate a radio signal of interest from all other radio signals received by the antenna. An amplifier amplifies the radio signal of interest to a level suitable level for processing. A local oscillator generates a local oscillator signal for a mixer to down convert the amplified radio frequency signal from one frequency to a different lower frequency. The converted frequency signal is further filtered, amplified, demodulated, and decoded into a usable form, such as sound, pictures, digital data, measurement values, navigational positions, etc.
An RF transmitter or a transmitter portion of an RF transceiver is an electronic circuit that receives an input signal, such as sound, pictures, digital data, measurement values, navigational positions, etc. The input signal is processed by being encoded, modulated, filtered, and amplified into an electronic signal. A local oscillator generates a local oscillator signal for a mixer to up convert the electronic signal from one frequency to a different higher frequency. The converted signal is further filtered and amplified to a level suitable for transmission. The amplified signal is radiated by an antenna to transmit the amplified signal as a radio frequency signal at a particular frequency.
An RF transmitter embodied as cellular phone, for example, may be employed in an RF communication system having multiple frequency bands associated with multiple air interface processes, providing services such as sound (e.g., voice), data (e.g., video, internet, text, etc.)3, location positioning (e.g., GPS), for example. To communicate over one or more of the multiple frequency bands, at the same time or different times, the cellular phone must be provided with receiver and transmitter functions compatible with the RF communication system. As summarized above, each of a receiver and a transmitter have many complicated functions to provide RF communications. If each receiver and transmitter were duplicated for each of the multiple frequency bands of the RF communication system, the cellular phone would become too big and too expensive. It would be desirable to provide a cellular phone with efficient receiver and transmitter functions to be compatible with an RF communication system having multiple frequency bands, without adding to the size or cost of the cellular phone.
Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art of RF transceiver designs, through comparison of such systems with some aspects of the present invention, as set forth in the remainder of the present application with reference to the drawings.